Full-wave rectifier with glow cathode



April 9, 1929. H. J. 'SPANNER 1,708,852

FULL WAVE RECTIFIER WITH GLOW CATHODE Filed Jan. 25, 1925 INVENTOR hZ/VS J046777M SPAN/Vt ZM/KQZLm/Q K ATTORNEYS Patented Apr. 9 192 9. V v I UNITED STATES PATENT OFFICE.

HANS JOACHIM SPANNER, OF BERLIN,.GERMANY, ASSIGNOR TO DR. ERICH F. HUTH G. M. B. H., OF BERLIN, GERMANY.

FULL-WAVE RECTIFIER WITH GLOW CATHODE. Application filed January 23, 1925, Serial No. 4,358, and in Germany January 25, 1924.

This invention relates to rectifiers with consequently better utilization of a discharge low cathode which may consist of a metal vessel the anode is caused to glow by the filament, for instance a tungsten filament or electrons acting upon the same so that it beof an electrically conducting basis wluch 1s comes also a source of electron em1ss1on. If

5 covered entirely or partly by a layer of oxlde. the anode has no coating layer favouring the 60 These cathodes were heated hitherto by a electron emission but only the cathode proper heating battery which was switched in porthe quantity of the electrons emitted Wlll premanently during the operation of the clecponder-ate on the glow cathode 1n comparh tron discharge tube and had consequently son with the quantity of electrons lssuing to be of corresponding size and requu-cd to trom the anode, even 1n the case that un1- 65 be recharged. lateral current conductrvity from the cathode In this invention the cathode heating batto the anode results owing to the prepondertery is rendered unnecessary during the ance of the electron emlsslon of one of the two operation proper. The invention consists in glowing electrodes.

heating the glow cathode during operation The glowing of the anode can be ex- 70 by the electron current WlllCll flows out of it ploited n full wave rectlfiers n an especially v to an anode so that the capability of the glow economical manner. According to the 1ncathode to emit electrons is directly 1nainvention the anode, which is concentrically tained. It is therefore no longer necessary d sposed about the glow cathode, s subdito switch the heating battery in during the vided 1nto two parts by a slot, which 1s as 75 time the tube is really used.- The heating narrow as possible. Each part of the anode battery or other source of heat is switched has its indrvlduahcurrent supply. In this in only for a very short time, usually for a manner 1t is possible to employ one glow fraction of a second. in order to cause the cathode rectifier tube as a full wave rectifier.

glow cathode to glow whereupon it is The narrow slot is such an insignificant alterswitched out immediately as soon as the anode ation 1n the anode that there are for both current (emission of electrons) starts. The phases the same thermic conditions when the heating battery can therefore be of very lOW anode 1s glow1ng. As regards the thermic efficiency. conditions the similarity of the two parts of 30 This self-heating of the cathode by the electhe anode can be increased by filling the tron emission current can, as mentioned narrow gap between the same with a material above, be used even for ordinary filamentwhich, although being electrically insulating, or plate cathodes, which are made for mis thermically conducting. stance of tungsten or other convenient mate- The material must however 35 rial. The application is further favoured ture in question emit electrons only in a very by using an oxide layer of alkaline earth limited degree. Zirconium oxide possesses metals or of other convenient combination for instance all these properties. The arand manufacture, This oxide layer ofiers rangement presents the further advantage a higher resistance against the passing of that, in contradistinction to the commonly 40 the current, than uncoated electric conductused full wave rectifiers of the Wehnelt type ing wires ofl'er. The electron or the anode and others, the distance between the two current traversing the coating layer must anodes and the glow cathode may be contherefore overcome a greater resistance when siderably smaller wherefrom results a more traversing this coating layer and by selectfavorable repartition of potential and a reing the thickness of the oxide layer accordduction of the prejudicial influence of the ingly, it is possible to bring the glow cathode space charge. It has thus become possible to any desired glowing temperature with the to transform in both phases even comparaaid of the so-called Joule elfect which is thus tively low alternating current voltages Withproduced. out the necessity to use artificial heating.

5 The use of a coating layer not only in- The automatic heating of the glow cathode creases the emission of electrons as compared is further favoured by the anode cylinder with the emission obtained by means of the which tightly encloses the cathode, owing to commonly used metallic conducting wires the radiation of heat from the anodes which but also presents still another advantage. It are brought to the glowing state, by giving has become known that at greater load and corresponding dimensions to the tube. A

at the temperaprising two anodes arranged at a comparatively great distance the one from the other. The improved full wave rectifier is shown by way of example on the accompanying drawing wherein Fig. 1 illustrates a perspec tive view of one form of the anode structure of this invention; Fig. 2 illustrates a perspective View of a modified form of this invention and Fig. 3 shows a perspective view of another modification of this invention. Like reference characters designate similar parts throughout the drawings.

In Fig. 1 the two cemented parts a, Z) of the anode cylinder have the leading-in wires 0, (Z. The glow cathode or filament e is stretched in the axis of the cylinder. Current is supplied to the filament a through the conductors f, g. The anode may also be in the form of a hollow body of some shape other than cylindrical. In this invention it is essential that the anode encloses the cathode. Instead of the slot being perpendicular to the axis of the cylinder two slots disposed in the direction of the axis cylinder may be provided, as shown in Fig. 2. An anode of the shape shown in Fig. 3 would also iulfillthe essential requirements of the invention, only it would have a less desirable effect as regards the good and uniform repartition of temperature to both anode parts.

The new arrangement can also be used with advantage for the rectification of multi-phase currents as it is only necessary to subdivide the anode'by several slots into several parts.

By making the anode surround the glowing cathode, excessive radiation of heat from the cathode is prevented, and therefore the cathode can be more easily maintained at the proper high temperature. I claim 7 1. A'full wave rectifier comprising a glow cathode designed to be maintained by the discharge current at the required glowing temperature and an anode subdivided into at 50 least two parts electrically insulated the one from the other to be joined to different circuits but thermally connected the one with the other and enclosing the cathode.

2. A full wave rectifier in which the anode 55 is subdivided by slots filled with an electrically non-conducting but thermally conducting strongly electro-negative material.

In testimony whereof I aiiix my signature.

DR. HANS J OACHIM SPANNER. 

